x86_64: vga: improve text printing code

5 files changed, 70 insertions, 20 deletions

diff --git a/source/arch/x86_64/include/arch/boot/pointers.hpp b/source/arch/x86_64/include/arch/boot/pointers.hpp
index 052b115..dcd14fe 100644
--- a/source/arch/x86_64/include/arch/boot/pointers.hpp
+++ b/source/arch/x86_64/include/arch/boot/pointers.hpp
@@ -6,7 +6,6 @@
 namespace teachos::arch::boot
 {
   extern "C" std::byte const multiboot_information_pointer;
-  extern "C" std::byte * vga_buffer_pointer;
 }  // namespace teachos::arch::boot
 
 #endif
\ No newline at end of file
diff --git a/source/arch/x86_64/include/arch/video/vga/text.hpp b/source/arch/x86_64/include/arch/video/vga/text.hpp
index 04b74d1..c9a79b8 100644
--- a/source/arch/x86_64/include/arch/video/vga/text.hpp
+++ b/source/arch/x86_64/include/arch/video/vga/text.hpp
@@ -1,12 +1,59 @@
 #ifndef TEACHOS_ARCH_X86_64_VIDEO_VGA_TEXT_HPP
 #define TEACHOS_ARCH_X86_64_VIDEO_VGA_TEXT_HPP
 
-#include <cstddef>
+#include <cstdint>
 #include <string_view>
 
 namespace teachos::arch::video::vga::text
 {
-  auto write(std::string_view text, std::byte color) -> void;
-}
+  enum struct color : std::uint8_t
+  {
+    black,
+    blue,
+    green,
+    cyan,
+    red,
+    purple,
+    brown,
+    gray,
+  };
+
+  enum struct foreground_flag : bool
+  {
+    none,
+    intense,
+  };
+
+  enum struct background_flag : bool
+  {
+    none,
+    blink_or_bright,
+  };
+
+  struct attribute
+  {
+    color foreground_color : 3;
+    enum foreground_flag foreground_flag : 1;
+    color bacground_color : 3;
+    enum background_flag background_flag : 1;
+  };
+
+  static_assert(sizeof(attribute) == 1);
+
+  namespace common_attributes
+  {
+    [[maybe_unused]]
+    auto constexpr gray_on_black = attribute{color::gray, foreground_flag::none, color::black, background_flag::none};
+
+    [[maybe_unused]]
+    auto constexpr green_on_black = attribute{color::green, foreground_flag::none, color::black, background_flag::none};
+
+    [[maybe_unused]]
+    auto constexpr white_on_red = attribute{color::gray, foreground_flag::intense, color::red, background_flag::none};
+  }
+
+  auto clear(attribute attribute = common_attributes::gray_on_black) -> void;
+  auto write(std::string_view code_points, attribute attribute) -> void;
+}  // namespace teachos::arch::video::vga::text
 
 #endif
\ No newline at end of file
diff --git a/source/arch/x86_64/src/boot/boot.s b/source/arch/x86_64/src/boot/boot.s
index 45f261e..7b4e193 100644
--- a/source/arch/x86_64/src/boot/boot.s
+++ b/source/arch/x86_64/src/boot/boot.s
@@ -362,11 +362,7 @@ _transition_to_long_mode:
     mov %rax, %fs
     mov %rax, %gs
 
-    /* Clear the screen */
-    mov $0x0f200f200f200f20, %rax
-    mov $0x0b8000, %rdi
-    mov $500, %rcx
-    rep stosq
+    movl $0xb8000, (vga_buffer_pointer)
 
     call _init
 
diff --git a/source/arch/x86_64/src/kernel/main.cpp b/source/arch/x86_64/src/kernel/main.cpp
index 9ea756a..26ae730 100644
--- a/source/arch/x86_64/src/kernel/main.cpp
+++ b/source/arch/x86_64/src/kernel/main.cpp
@@ -6,10 +6,9 @@ namespace teachos::arch::kernel
 {
   auto main() -> void
   {
-    video::vga::text::write("TeachOS is starting up...", static_cast<std::byte>(0x4f));
-    while (true)
-    {
-      asm volatile("hlt");
-    }
+    using namespace video::vga;
+
+    text::clear();
+    text::write("TeachOS is starting up...", text::common_attributes::green_on_black);
   }
 }  // namespace teachos::arch::kernel
diff --git a/source/arch/x86_64/src/video/vga/text.cpp b/source/arch/x86_64/src/video/vga/text.cpp
index 11e3b1a..df61ce6 100644
--- a/source/arch/x86_64/src/video/vga/text.cpp
+++ b/source/arch/x86_64/src/video/vga/text.cpp
@@ -5,25 +5,34 @@
 
 #include <algorithm>
 #include <string_view>
+#include <utility>
 
 namespace teachos::arch::video::vga::text
 {
 
   namespace
   {
-    auto constinit text_buffer = teachos::boot::asm_pointer{boot::vga_buffer_pointer};
+    auto constexpr default_text_buffer_address = 0xb8000;
 
-    auto write(char character, std::byte color) -> void
+    extern "C" std::pair<char, attribute> * vga_buffer_pointer;
+    auto constinit text_buffer = teachos::boot::asm_pointer{vga_buffer_pointer};
+
+    auto write(char code_point, attribute attribute) -> void
     {
       auto & p = *text_buffer;
-      (*p++) = static_cast<std::byte>(character);
-      (*p++) = color;
+      (*p++) = std::pair{code_point, attribute};
     };
   }  // namespace
 
-  auto write(std::string_view text, std::byte color) -> void
+  auto clear(attribute attribute) -> void
+  {
+    *text_buffer = reinterpret_cast<decltype(text_buffer)::pointer>(default_text_buffer_address);
+    std::ranges::generate_n(*text_buffer, 2000, [&]{ return std::pair{' ', attribute}; });
+  }
+
+  auto write(std::string_view code_points, attribute attribute) -> void
   {
-    std::ranges::for_each(text, [&](auto character) { write(character, color); });
+    std::ranges::for_each(code_points, [&](auto code_point) { write(code_point, attribute); });
   }
 
 }  // namespace teachos::arch::video::vga::text
\ No newline at end of file